What does "DRSN" signify in a METAR report?

In a METAR report, "DRSN" signifies drifting snow. This term is used to indicate the presence of snow that is being moved by the wind, resulting in reduced visibility and potentially affecting surface conditions. Drifting snow can occur during or after a snowfall, especially when windy conditions are present.

The presence of drifting snow is important for pilots and meteorologists because it can significantly impact air travel safety and ground transportation. Drifting snow can create hazardous conditions, such as snow drifts on runways or reduced visibility in the air. Recording this information helps provide a complete picture of current weather conditions.

The other options describe different phenomena that are not indicated by "DRSN." Dust storms, dry snow, and deep frost have distinct notations in METAR reports, ensuring clarity and precision in weather communication.